The present invention relates to an adjustment device, in particular for use with adjustable flap valves.
An adjustment device of a type involved here finds application especially in heating, air-conditioning and ventilation systems for opening and closing a control element of a flap valve. The respective adjusting movement depends hereby on the intended purpose. For example, in case of fire, it may be necessary to open or close the flap valves, whereby it is demanded that the pivoting movement of the control element should not be assumed by the drive motor but by an energy storage member, such as a tensed spring, so as to ensure execution of the necessary movement, even when the drive motor fails to operate as a consequence of external impacts, e.g. elevated temperature. The energy storage member is hereby biased when the control element is moved from the base position into the operative position that is normally assumed by the control element. It may, however, also be necessary to move the control element into different positions at short intervals in response to a change in temperature. These types of drives are called spring-return mechanisms.
Adjustment devices of the type involved here are typically installed in narrow spaces so that their compactness becomes an issue.
Oftentimes it is desired to ascertain the position of the control element or of a component of the drive train, or there may be a need to allow a movement of the control element or of a component of the drive train to a particular position. This is typically implemented by means of a recorder which is part of the adjustment device. Examples of recorders include a potentiometer or a variable resistor. In conventional adjustment devices, the potentiometer has a control member which is linked to a component of the drive train or to the control element via a respective gear mechanism or similar drive block. This approach results in an undesired increase in the number of components. Moreover, it is unavoidable that a gap between gear wheels or an elastic deformation of components adversely affects the outcome.
It would therefore be desirable and advantageous to provide an improved adjustment device which obviates prior art shortcomings and which is compact in structure, while yet being reliable in operation.